[SystemSafety] Electrical Safety, Fire Safety

Peter Bishop pgb at adelard.com
Fri Jun 16 14:36:13 CEST 2017


Re Grenfell Tower.

This is just speculation on my part, but I wonder if the combination
of new windows and cladding made things much worse.

The old windows were fitted into the (non-inflammable) masonry walls.
The new windows were fitted further out - fitted flush with the outside
of the cladding. There is some kind of surround between the extended
window aperture and the inside wall - but no idea how flame-proof that is.

There is an intentional air gap between cladding and masonry wall (for
drainage), so there is a potential flame path from fire *inside* the
window through a breach in the aperture surround and up into the masonry
cladding gap.

Thereafter the chimney effect of the air-gap behind the cladding could
ensure the cladding filler was set ablaze all the way up to the top of
the building.

As I said this is just speculation, but it is a common problem to make
modifications that violate the original design safety concept
- in this case the change could have the violated the design concept
that rooms are compartmentalised to restrict the spread of fire.

Peter Bishop

Adelard

On 16/06/2017 12:47, paul_e.bennett at topmail.co.uk wrote:
> On 16/06/2017 at 12:22 PM, "Peter Bernard Ladkin" <ladkin at causalis.com> wrote:
>>
> 
> [%X]
> 
>> Six years later, are such robots available to investigate the 
>> Grenfell Tower wreckage, said to be
>> unstable? If not, shouldn't we try to ensure some are available 
>> for the next disaster in enclosed
>> spaces?
> 
> They are using flying drones and specialists dogs with cameras to search
> where fire-crew are not able to go at present.
> 
>> Issues about building safety are difficult. I have my problems 
>> nowadays with large buildings and
>> escape routes when I am staying in hotels. Newer ones mostly seem 
>> OK, but I am also aware that
>> evacuation is still more art and luck than science, as Chris 
>> Johnson showed a decade or so ago. It's
>> a key business in ship classification for cruise vessels, but even 
>> so it doesn't work super-well, as
>> we learnt with the Costa Concordia. You have potentially 5,000-
>> 6,000 people on some of the newer craft.
> 
> Evacuation policy and escape routes really do need looking at for 
> buildings with significant altitude (more than two stories). With Grenfell
> tower, they only had one escape route which became flooded with thick
> smoke quite quickly and with the advice that many residents were given
> about staying put, seemed to have been wrong headed in that situation.
> 
> There has been a lot of talk, about Grenfell Tower, about the inherent 
> fire integrity of such buildings, but there is suspicion that such inherent
> fire integrity was probably compromised by the refurbishment works
> carried out just over a year ago.
> 
>> Besides electrical safety, the issue of fire-resistent cladding is 
>> not new. The issues of sprinklers
>> in large buildings, and appropriately-functional evacuation 
>> routes, are perennial. Evacuation is a
>> tricky business, as Chris Johnson and Karster Loer know. Karsten, 
>> BTW, drew up the evacuation plans
>> for a open-air rock concert last year, at which there was a 
>> violent storm on the first day and
>> everyone was evacuated. It's nice to have it proved that your 
>> plans work! Evacuation and crowd
>> control came into prominence in Germany with the Love Parade 
>> disaster in Duisburg in 2010.
> 
> The retro-fitting of sprinklers systems have been recommended for such
> buildings but for such tall buildings that becomes a major undertaking in
> terms of design and water supply.
> 
> I have seen reports on mister systems that enable rapid cooling of fires,
> which use much less water, so it should be incumbent on those 
> responsible for such buildings to examine the best technology to aid in
> fire control (rather the the minimal to comply with regulations).
> 
> Regards
> 
> Paul E. Bennett IEng MIET
> Systems Engineer
> 

-- 

Peter Bishop
Chief Scientist
Adelard LLP
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